Interference with platform wireless operation caused by noise coming from system buses and clocks internal to a device, referred to as platform noise, is a growing concern. The impact of such platform noise is becoming more severe in smaller, more radio-rich platforms and frequently forces higher costs, delayed product launches due to redesign and retest cycles, and post launch end user complaints.
Previous solutions include metallic shielding, Radio Interference Mitigation (RIM) technology, and Adaptive Clocking Technology (ACT), as some examples. Shielding is the predominant industry solution but is undesirable due to materials and tooling costs as well as impacts on form factor flexibility which for example impacts airflow, weight, and product thickness. The RIM approach adaptively cancels platform clock interference in the radio. ACT addresses clock noise at the source rather than at the radio wherein platform clock frequencies are shifted slightly to minimize harmonic overlap with wireless bands. When used in combination, ACT and RIM may provide helpful mitigation of clock noise but such approaches do not address noise from bus traffic. ACT is furthermore limited by tight clock specifications in some cases.
There is currently no effective electronic solution in production for mitigation of bus noise. One proposed approach involves binary encoding of bus data before transmission. However, the specific coding technique must be customized for each bus type, for example double data rate (DDR) memory buses, peripheral component interconnect express (PCIe) buses, universal serial bus (USB) buses, and so on, in order to minimize the inherent impact that such coding has on bus data throughput and power, as well as to reduce required changes to existing industry standards and third-party components.
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